All of the maps were painstakingly drawn by hand, scanned and then optimized using Fireworks. The source data for the maps came from the mapping room. I then spent hours walking the pathways and turning round and around to note the relative position of rocks, trees, buildings and the islands themselves. During the course of this cartographical journey I discovered quite a few continuity errors. Most notably a MagLev station that should be underwater but isn't!
Anyway, I hope these maps assist the lost and frustrated in their journey through Riven.
If you have found this walkthrough useful, discovered an error or have a suggestion then let me know: feedback.